In this austere black-and-white character study — framed in the boxy aspect ratio of another era — Poland is a country and culture locked in the twin tragedies of World War II and postwar communism. As a place painfully suspended in time, it makes the perfect backdrop for people weighed down by personal and political histories so heavy and oppressive that they threaten to crush them not just psychically, but also physically.

Anna (Trzebuchowska) is a young novitiate nun who has been living for years in the rural convent where she grew up as an orphan when the Mother Superior informs her that she has a blood relative living in Gdansk. Ordered by the nun to make contact before taking her vows, Anna travels to visit Wanda (Agata Kulesza), who answers the door smoking a cigarette while a one-night-stand hurriedly dresses in the bedroom.

The two women end up spending the next few days together, traveling to their family’s former home and dredging up the myriad contradictions that animated Poland during the war, when Catholics either turned on or saved their Jewish neighbors, and after which citizens either collaborated with or resisted the Stalinist purges. Her face a despairing, hard-bitten mask of culpability and tenacious grit, Wanda refuses to tailor her behavior to suit the prim, protected Anna: “I’m the slut and you’re the little saint,” she says bitterly at one point.

But eventually, these two temperamentally disparate heroines achieve an improbable meeting — even melding — of the minds, as “Ida” sends each woman on an individual journey that seems as inevitable as it is quietly shocking. Pawlikowski, best known for his 2004 coming-of-age drama, “My Summer of Love,” makes a series of wise choices throughout “Ida,” starting with casting Trzebuchowska — who reportedly was discovered in a Warsaw coffee shop — and extending to his sensitive exploitation of a tonal palette dominated by marmoreal shades of gray.

For a film about grave moral questions and contradictions, “Ida” possesses more than its share of sensory pleasures, among them a soundtrack dominated by the silky sounds of John Coltrane and a command of time and place that allows viewers to feel that they’ve been on the same grim road as the story’s intriguing protagonists.

Each and every detail accrues to create a vivid, unforgettable portrait, and all are absorbed and reflected by Anna, portrayed by Trzebuchowska with the transparency and wonder of a woman for whom not just history but secular life itself is almost totally abstract. She’s the ideal foil for “Ida’s” gnarliest themes, which play out with messy immediacy in the life of her aunt, a woman haunted by the cumulative effects of accommodating the most disastrous chapters of Poland’s political history.

“Ida,” like the recent Romanian film “Child’s Pose,” joins a slew of films from the former Eastern Bloc that seek to create something coherent and honest from a bewildering and painful past. Pawlikowski has proven to be an exceptionally sensitive and poetic master of that form.